Surface modeling and geometry capture are used in a range of computer assisted fields including Augmented Reality (AR), Virtual Reality (VR), computer graphics, medical imaging, visualization systems, and artistic fields. To support these systems, a variety of human controllable input devices and techniques have been developed to assist the modeling process. Clay and similar materials have been used for sculpting real models for many years.
One technique used to capture physical geometries is to measure the physical object and manually enter each dimension. Commercially available laser scanners allow the capture of complex geometries and generate digital presentations having a high polygon count. Such scanners are not designed for real-time manipulation tasks and deformations and corrections are usually needed to correct the captured model. Some systems use a number of photographs taken from different angles; which are processed manually to create a representation of the geometry of the photographed article. The Tinmith system uses pinch gloves and fiducial markers to track a user's thumbs allowing a range of computer aided design (CAD) like interaction techniques including construction at a distance, AR working planes, infinite carving planes, orthogonal laser carving, and creating a surface of revolution using AR. VR systems such as Virtual Clay provide an interactive freeform modeling environment. There also exists an interactive sculpting framework that encompasses modeling techniques based on the subdivision of solid geometries. It supports clay like manipulations, and more, allowing intuitive sculpting to be performed with physics based responses and haptic feedback using a phantom device.
Other input devices allow the creation, manipulation, and navigation of 3D geometries. The “two-4-six” input device is designed to support 3D manipulations with six degrees of freedom. It was designed for interactive presentations of virtual objects using multiple sensors as inputs. Orientation is tracked using gyroscopes and a rocker leaver, and an elastic touchpad is used to control rotation, translation, and manipulation operations. The Cubic Mouse is a cube-shaped input device with three rods that protrude through the faces of a cube. By pulling and pushing on the rods, motion is specified on the corresponding X, Y and Z axis. This input device also has 6 degrees of freedom (DOF) tracking to allow registration with a virtual environment.
Malleable surfaces are tracked using a camera mounted underneath a silicon membrane. The silicone membrane has colored dots printed on its surface that are observed by the camera. Deformations can then be calculated in software allowing a reconstruction of the silicon's surface shape. A limitation of this form of malleable surface is that to construct a malleable spherical prop where all surfaces can be squashed is not simple since a support structure is required to hold the stretched silicon in place preventing depression in some locations.